The design and development of commercial AAA videogames is a difficult and complex endeavor. It involves large development teams that together aim to create high quality, entertaining games that sell well. Up to now, very few scholars have documented or problematized this practice. This thesis presents a study of the design practices in big game development studios that make commercial AAA videogames. The study focuses on the so called ideation part of videogame development, in which the design ideas are generated, developed and communicated in the work team. The primary data comes from interviews conducted with seven Swedish game developers, but a large quantity of secondary data has also been used. The study shows that the design practice in many studios is to focus on the player experience instead of game features. To secure the intended player experience, the studios have moved away from "big design up front" in the form of classical game design documents, and are instead using a variety of verbal, visual and audial tools to articulate and communicate their vision of the game-to-be. In the thesis, I coin the term lodestars to denote these articulations of the main game concept and the intended player experience. I then move on to describe, exemplify and categorize them. The main purpose of lodestars is to allow everyone in the development team to make design choices in line with a commonly shared design vision in order to create a unified player experience.